1. Field of the Invention
The present invention relates to a draw out type air circuit breaker, and in particular to an interlock apparatus for indicating the position in a draw out type air circuit breaker which is capable of indicating accurately a disconnected position, a testing position and a connected position when a breaker is pushed in /pulled out from a cradle.
2. Description of the Prior Art
Generally, an air circuit breaker is installed between an electrical load and an electrical power source in order to protect the load equipment such as a motor and a converter, etc. and a line from an abnormal current (a short circuit, a ground fault, an excess current) generated in an electric circuit such as a power transmission/distribution line and private electricity generating facilities, etc., it means a breaker using air as a medium is for extinguishing an arc generated while opening/closing of contacts.
An air circuit breaker is divided into a fixed type fixedly installed between power source and a load and a drawer type in which a breaker is movable so as to be separated from power source and a load in order to facilitate maintenance and secure stability.
FIG. 1 is a side view illustrating a state in which a cradle is separated from a breaker body in a general draw out type air circuit breaker.
The general draw out type air circuit breaker includes a cradle 100 having an opened side and installed a power source connection terminal 60 connected to power source and a load connection terminal 62 connected to a electrical load equipment, a breaker body 200 movable so as to be pushed in or pulled out from the cradle 100 and performing a circuit cut-off operation in an abnormal current occurrence, and an interlock apparatus 300 for indicating a position of the breaker body 200 by being interlocked with a translocation of the breaker body 200 when the breaker body 200 is pushed in or pulled out from the cradle 100.
Herein, connectors 64, 66 are respectively connected to the power connection terminal 60 and the load connection terminal 62 of the cradle 100, the connectors 64, 66 are respectively inserted into a power source connection terminal 68 and a load connection terminal 70 projected from the breaker body 200 and are electrically connected.
And, the cradle 100 includes a guide rod 72 for guiding the translocation of the breaker body 200 when the breaker body 200 is pushed in/pulled out.
FIG. 2 is a side view illustrating an interlock apparatus of a drawer type air circuit breaker in accordance with the prior art, and FIG. 3 is a front view illustrating the interlock apparatus of FIG. 2 viewing from the right side.
The interlock apparatus in accordance with the prior art includes a base frame 102 fixed to the breaker body 200, shown in FIG. 1, a lead screw 104 supported by the base frame 102 so as to be rotatable, a screw pipe 106 fixed to the cradle 100 and be inserted by the lead screw 104, an interlock apparatus 300 installed on the base frame 102 and for indicating a position of the breaker body 200 when the lead screw 104 is meshed with the screw pipe 106, and a locking device 110 connected to the interlock apparatus 300 and locking a position when the breaker body 200 is placed at a disconnected position, a testing position and a connected position.
The interlock apparatus 300 includes a lead bar 112 disposed in parallel with the lead screw 104, contactable to one wall surface of the cradle 100 and retreating relatively when the lead screw 104 is meshed with the screw pipe 106 and linearly moves, a cam 114 connected to the lead bar 112 and installed in the base frame 102 so as to be rotatable for transforming a horizontal linear movement from the retreating lead bar 112 into rotating movement, and a indicating means 150 connected to the side of the cam 114 and for indicating a position of the breaker body 200 in accordance with the rotation of the cam 114.
The lead bar 112 is constructed in one body, one portion of the lead bar 112 is extended in parallel with the lead screw 104, the other portion of the lead bar 112 is constructed as a curved rod shaped member having a predetermined length so as to be inserted into a slot 118 provided in the cam 114.
And, a breakaway preventing member 120 for preventing a breakaway of the lead bar 112 from the slot 118 is installed to the end of the lead bar 112 inserted into the slot 118. And, a return spring 122 for providing an elastic force on the lead bar returning to an original position after operation is installed between the breakaway preventing member 120 and the base frame 102.
The cam 114 has a hinge portion 126 so as to be rotatably installed on the base frame 102, a slot 118 in which the lead bar 112 is inserted is formed at the lower portion of the cam 114 so as to be curved a certain times at a predetermined angle, and a connection pin 124 connected to an indicating plate 116 placed at the front of the hinge portion 126.
As depicted in FIGS. 2 and 3, the indicating means 150 includes the indicating plate 116 linearly moving up or down when the cam 114 rotates by being inserted by the connection pin 124 installed to the cam 114 and having a color indicating portion (not shown) on the upper front surface for indicating a position of the breaker body 200 with colors. A front plate 130 is fixedly installed to the base frame 102 at the front of the indicating plate 116 and having three indicating windows 138, 140, 142 for respectively indicating a position (a disconnected position, a test position, a connected position) of the color indicating portion of the indicate plate, a handle insertion hole 134 in which a handle (not shown) for rotating the lead screw 104 is inserted at the center portion. A guide plate 132 placed at the rear of the indicating plate 116 and for guiding the up or down movement of the indicating plate 116.
FIGS. 4 and 5 are state diagrams illustrating an operation state of a main parts of an interlock apparatus in accordance with the prior art.
In an interlock apparatus of a air circuit breaker in accordance with the prior art, in order to connect the cradle 100 to the breaker body 200, the breaker body 200 is placed on a guide rod 72 of the cradle 100 and is pushed in, accordingly the breaker body 200 is moved into the cradle 100. When the lead screw 104 contacts to the screw pipe 106 according to the moving of the breaker body 200 and a user rotates the lead screw 104 by using the handle, the lead screw proceeds into the screw pipe 106 while rotating.
Then, the two connection terminals 68, 70 projected from the breaker body 200 are connected to the two connectors 64, 66 installed to the cradle 100, accordingly the power source terminal 60 and the load terminal 62 are connected.
When the lead screw 104 proceeds, the lead bar 112 contacts to one wall surface of the cradle 100, herein the lead bar 112 moves in a direction opposite to the lead screw 104. As described above, when the lead bar 112 retreats, it rotates the cam 114 in the counter-clock wise while moving along the slot 118 of the cam 114, by the rotation of the cam 114 the indicate plate 116 moves up. Herein, the indicating portion 40 provided on the indicating plate 116 is displayed one of the three indicating windows 138, 140, 142 of the front plate 130 in order to indicate a present position of the breaker body 200.
In more detail, when the two connection terminals 68, 70 projected from the breaker body 200 and the connectors 64, 66 installed to the cradle 100 are not connected each other, the circuit is in the cut-off state, at the same time the lead screw 112 is totally separated from the screw pipe 106, the indicating portion 40 of the indicating plate 116 is displayed on the lowest indicating window 138 of the three indicating windows. Accordingly, the user recognizes the preset position as a disconnected position.
And, the lead screw 104 proceeds with a predetermined distance, the cradle 100 and the breaker body 200 are connected each other electrically and mechanically, when an electrical connection between the cradle 100 and the main electrical power source (high voltage power source supplied to the actual circuit between the power source and the load) is cut-off, control electrical power (low voltage power such as AC 110 volt for testing the breaker) is applied to the terminal 60, when the breaker body 200 reaches the testing position in which a user checks and tests each part of the breaker, the indicating plate 116 moves upwardly with a predetermined distance, the indicating portion 40 is displayed on the middle indicating window 140 of the three display windows, accordingly the user recognizes the breaker body 200 is at the testing position. When the lead screw 104 proceeds completely, the connection terminals 68, 70 are inserted into the connectors 64, 66 installed to the cradle 100 and reaches the connected position in which main electrical power source is supplied to the circuit between the power source and the load, the indicating portion 40 is displayed on the upper indicating window 142, accordingly the user recognizes the breaker body 200 is at the connected position.
However, in the interlock apparatus of the air circuit breaker in accordance with the prior art, the lead bar for rotating the cam is provided in one body as a rod having a predetermined length and there is no additional guide member for supporting and guiding the movement of the lead bar, so it is easy for the lead bar to be deformed or bent and a translocation of the indicating plate becomes inaccurate, accordingly it is impossible to indicate an accurate position of the breaker body.
In addition, there is a predetermined tolerance in order to facilitate the operation and the assembly of the lead bar, the tolerance is increased in accordance with the time passing, accordingly it is impossible to control a translocation accurately.
In order to achieve the above-mentioned problems, it is an object of the present invention to provide an air circuit breaker having an interlock apparatus which is capable of controlling a translocation accurately by preventing a deformation and a bent of a lead bar and minimizing a tolerance in production by constructing the lead bar as two separated bars and having a guide means guiding movement of the lead bar.
In order to achieve the above-mentioned object, in an air circuit breaker comprising a movable breaker body having a power source terminal and a load terminal and connecting or disconnecting a circuit between power source and a load;
a cradle electrically and mechanically connected to or separated from the breaker body in accordance with movement of the breaker body and having a connector electrically and mechanically connected to the breaker body, a screw pipe for guiding the connected to or separated from the breaker body and a power source terminal and a load terminal respectively connected to an electrical power source and an electrical load;
a base frame fixed to the breaker body;
a lead screw supported by the base frame so as to be rotatable and movable to a position for being inserted into the screw pipe and a position for being separated from the screw pipe;
a interlock apparatus installed on the base frame and for indicating a position of the breaker body such as a disconnected position in which the breaker body is totally separated from the cradle, a testing position for testing the breaker body and a connected position in which the breaker body is connected to the cradle;
the interlock device comprising;
a first lead bar extended from the base frame toward the front end of the lead screw in parallel with the lead screw and for generating a dynamic power for indicating a position of the breaker body by moving in a direction opposite to a forward direction of the lead screw when the lead screw is inserted into the screw pipe;
a guide member installed so as to be movable on the lead screw in the base frame, connected to the first lead bar and performing a horizontal linear movement corresponded to the movement of the first lead bar;
a second lead bar constructed separately from the first lead bar, connected to the guide member inside the base frame and performing a horizontal linear movement corresponded to the movement of the guide member;
a spring installed on the lead screw inside the base frame and for applying an elastic force on the first lead bar in a forward direction of the lead screw;
a cam connected to the second lead bar and for transforming the linear movement of the second lead bar into rotating movement; and
an indicating means connected to the cam and for indicating a position of the breaker.